ANDRA.ANDRA History
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%center% Radioactive wave management scenario based on simplified
physicochemical processes
For each application, ANDRA has been considering the use of HPC
facilities for several years, through the development or new or use of
existing methods and tools that would lead to improve the level of
representation, in terms of geometry and/or physical processes. Thus,
ANDRA is particularly interested in specific methods such as domain
decomposition (space and time), parallel solvers, efficient
preconditionners and solvers that would allow to take into account
many millions of elements.
Simulations are based on a large data set derived from an intensive
characterization program. They are thus complex because they require a
detailed geometry, with contrasts of parameters to manage, and applied
to physical processes, with couplings, and non-linear equations. Up to
now, in order to fulfill good understanding of the global system with
previous peculiarities, and to get knowledge and information with both
reasonable time and good accuracy, many simplifications are made,
whose levels depend on the efficiency of available numerical methods
and tools. Two levels of simulations are thus carried out:
* Complex physicochemical processes, involving strong couplings
(such as chemical-transport, 2 phase-flow with radionuclide
transfer, thermo-hydro-mechanics problems) but solved on small
systems with grids up to many thousands of elements.
* Simplified physicochemical processes (leak coupling) consisting
of modifying in space and time hydraulic and solute transfer
parameters, but solved on big systems with grids of many millions of
elements. Global system is splitted into embedded compartments whose
scales are bigger and bigger.
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The Performance Assessment Department from Research and Development Division is the entity involved in the [[http://www-sop.inria.fr/c2s_at_exa | C2S@Exa]]. The department is responsible of the phenomenological description and performance/safety assessment of the integrated disposal repositories and their geological environments. It provides phe- nomenological and conceptual description of the behavior of each repository and geological component during operating and post-closure periods, in space and time (thermal, chemical, mechanical, hydraulic- gas, radionuclide/toxic release and transfer), including uncertainties analysis. The objective is to achieve a relevant, traceable and justified data base on multiphysic understanding at all space and time scales, in order (i) to develop safety assessment of repositories, (ii) to contribute to choices of design concept, (iii) to contribute to monitor the repositories and their environments, and (iv) to contribute to define step by step operating of the repositories. To assess the objective, the department and its subcontractors set up and perform many numerical simulations, involving efficient and robust methods and tools, and sound link with characterization data. The department also supports definition, development, choice and implementation of relevant simulation tools for all agency activities.
In the field of phenomenological description and performance/safety assessment, ANDRA has to perform many numerical simulations, in particular to quantify flow and solute transfer in saturated or unsaturated porous media, from the waste package to the human being, and through the repository and geological environment. Simulations have to take into account many physical processes, applied to different components (from the waste packages to the geological media) and material (clay, concrete, iron, glass, etc.) on very large time (up to one million years) and scale (from centimeter to tens of kilometers.
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%center% Modeling context of radioactive wave management
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